Variable spacing mechanism for typewriting machines



A. LEHMANN Dec. 15, 1959 VARIABLE SPACING MECHANISM FOR TYPEWRITING MACHINES Filed April 20, 1956 2 Sheets-Sheet 1 A. LEHMANN Dec. 15, 1959 VARIABLE SPACING MECHANISM FOR TYPEWRITING MACHINES Filed April 20, 1956 2 Sheets-Sheet 2 wn-wroe 4; 51 44/052 ze/m wwv United States Patent VARIABLE SPACING MECHANISM FOR TYPEWRITING MACHINES Alexander Lehmann, Bischhofsheim, Kreis Hanan, Germany Application April 20, 1956, Serial No. 579,497

Claims priority, application Germany April 25, 1955 16 Claims. (Cl. 197-84) The invention relates to a typewriting business machine. More specifically the invention relates to a device for recording business machines for switching steps of various lengths with a pawl tooth that can be moved by various step lengths. In this device the carriage holding the platen is maintained in its rest position by the pawl tooth of a carriage switchgear engaging an escapement wheel, after the completion of each switch step. When pressing down a type key or the space key, the pawl tooth is disengaged from the escapement wheel by shifting the switching element, while the escapement wheel is at first retained by the simultaneous engagement of the fixed ratchet tooth. The pawl tooth advances under the action of a spring by an amount determined by stops, so that when the switching element is returned, it engages one of the following teeth in the direction of rotation of the escapement wheel. Thus it is possible to obtain various switch step lengths of the carriage.

The object of the invention is to provide a device of the above-mentioned type in such a way as to achieve a higher switching speed of the pawl tooth, a greater reliability of the switching mechanism, and the possibility of setting the carriage switchgear for a larger number of various switch step lengths. The device according to the invention can be used with great advantage for recording business machines, where different switch step lengths are to be effected for types of various widths. It is not limited, however, to these machines as it can also be used for space typing, that is, for a larger switch step for all types. The abovementioned advantages are achieved according to the invention in such a way that the pawl tooth is conducted in a track with a concave curvature in the direction of the axis of the escapement wheel.

An embodiment of the invention is illustrated by way of an example on the attached drawings, in which Figure l is an end view of a part of the carriage switchgear as seen in the direction of the arrow A in Fig. 2, as viewed from the front side of the machine, with the escapement wheel removed and indicated by broken lines; Fig. 2 is a vertical section through a part of the typewriter, as viewed from the left side of the machine; Fig. 3 is a horizontal section taken on the line 3-3 of Fig. 2; Fig. 4 is a perspective view of a detail; Fig. 5 is a side view of the upper part of a detail of Fig. 2; and Fig. 6 is an end view of another detail.

In the switch gear frame 1, Fig. 2, an escap'enient wheel 3 and a carriage driving wheel 4 rigidly connected therewith, are pivotally mounted on an axle or shaft 2. The escapement or switch wheel 3 according to the invention is provided with teeth 5 of a greater number than the teeth on the carriage driving wheel 4 engaging the carriage rack 6, preferably corresponding to a transmission 2,917,152 Patented Dec. 15, 1959 ratio of 1:3 or 1:5. On the axle 2 of the escapement wheel 3 there is also arranged a disk 8 provided with an annular groove 7 and rotatable with the escapement wheel 3.

Pivoted in bearings 9, Figs. 1 and 2, in the switchgear frame 1 is a switching element 11 carrying fixed ratchet tooth 10. In the switchgear frame 1 is also pivoted a second switching element 12 on bearings 13. The second switching element 12 is urged counterclockwise by a spring 14, Fig. 2, and its normal position presents an offset part 15, Fig. 4, arranged thereon to strike against a setscrew 16, Fig. 2, provided on the first switching element 11. At the same time, the first switching element 11 is urged clockwise by the spring 14, Fig. 2, and its normal position is determined by striking against the head of a screw 93 passing therethrough, Fig. l. The pivoting motion of the second switching element 12 is limited in the direction opposite to the force of the spring 14 by a stop 17, Fig. 2, secured on the switchgear frame 1.

On a web 94, Figs. 1 and 4, of the second switching element 12, a rocking lever 18 is pivoted on a journal 19. On the rocking lever 18 a bolt or pin 20 is secured which is contacted and embraced by an arm of a slide spring 21, Fig. 1, that projects in the annular groove 7 of the disc 8, secured on the escapement wheel 3. The rocking lever 18 is turned counterclockwise by the slide spring 21 upon rotation of the escapement wheel 3 during the step switching, until a pin 22 secured to the rocking lever 18 and protruding through a recess 24 in the second switching element 12, strikes against an upper edge 25 of the recess 24.

On the rocking lever 18 there is pivotally mounted on a pivot 28, a pawl 26, Fig. 2, having a pawl tooth 27 a slight distance from the escapement wheel 3. The pivot 28 is arranged according to the invention inside the cylinder 23, Fig. 2, formed by the teeth 5 of the escapement wheel 3.

The pawl 26 is urged clockwise by a spring 31 engaging an arm 29 and secured on :1 lug 30 of the rocking lever 18 and is urged as well by another spring 32 which is secured on a lug 33 of the second switching element 12, when the pawl tooth 27 is disengaged from the escapernent wheel 3, Fig. 1. Thus the pawl tooth 27 jumps forth and moves in a circular are about its pivot 28, that is, in a concave bent track 34 relative to the axle 2 of the escapement wheel 3. The pawl tooth 27 remains therefore in the range of the teeth 5, even with a larger projecting path, so that it can engage the respective tooth 5, after the return of the second switching element 12. The two springs 31 and 32 act on the pawl 25 at different points and in different directions, as may be seen from Figs. 1 and 4. They are preferably assembled with different initial stress or forces and have different spring characteristics. This prevents fluttering of the pawl 26 and of the pawl tooth 27 during the jumping and striking of the latter at the end of the movement. The pawl 26 is so ofiset that its upper part, serving as a support, lies with its arm 29 at a distance laterally of the escapement wheel 3, while the angular part 26a carrying the bent-off portion 35 is arranged nearer to the escapemcnt wheel 3. Naturally the movement of the pawl tooth 27 in the curved track 34 can also be obtained by other means.

On the first switching element 11 there is secured by fastening means 95, a stop 37, Fig. 1, arranged adjacent the teeth 5 of the escapement Wheel 3, substantially in the plane of the stop face 36 of the fixed ratchet tooth 10, the stop 37 being designed preferably as a spring member which serves as a stop for the pawl tooth 27 to complete the switch step. The stop 37 embraces the teeth 5 of the escapement wheel 3 preferably on two sides, as best seen in Fig. 6. The pawl tooth 27 engaging a tooth 5 of the escapement wheel 3 is therefore stressed on an angular line at the end of a switch step or jump of the carriage. A very small cross section suffices to absorb this stress. It is therefore possible to make the pawl tooth 27 and the pawl 26 of a very thin steel plate, preferably in one piece, for example by means of the bent-off portion 35. Due to the small mass of the pawl tooth 27 and the pawl 26, a very rapid and reliable switching motion of the pawl tooth 27 is achieved in the very short time available for the step switching.

On the switchgear frame 1 is also provided a fixed stop 38, Fig. 1, which limits the forward motion of the pawl tooth 27 after swinging away from the escapement wheel 3. 0n the first switching element 11 is secured another stop 97 which cooperates with the pawl tooth 27 during the return motion of the carriage.

On the switchgear frame 1 there is secured a bearing plate 39, Fig. 2. Pivotally mounted on a shaft 40, preferably arranged perpendicularly to the step wheel axle 2, are a plurality of switch levers 41, Fig. 2, adjacent to each other, each of which is provided with a stop face 42, Figs. 1 and 2, to cooperate with a bent-off portion 96, Fig. 4, of the pawl 26, and each lever 41 is provided with a stop face 43 for transmitting members 45 actuated by key levers 44. The switch levers 41 are urged clockwise by a spring 46, Fig. 2, their normal position being limited by striking against the lower edge of guide slots of a guide cam 47 secured on the switchgear frame 1.

In a U-shaped carrier 48, Fig. 2, secured on the switchgear frame 1, there is pivotally mounted a stirrup 49 on an axle or rod 50. The stirrup 49 is urged counterclockwise by a spring 52 acting on its shorter leg 51, the normal position being limited by a longer leg 53 striking against a setscrew 54 provided in the switchgear frame 1. The flange 55 of the stirrup 49 cooperates with a lug 56 of a push rod 57, which is connected with a space key lever (not shown). Another lug 59 of the push rod 57 cooperates with the lower switching element 11.

A bent portion 60, Figs. 4 and 5, of the rocking lever 18 engages a forked recess 61 of a lever 64 which is pivoted on a journal 62 of a plate 63 secured on the switchgear frame 1. The lever 64 can be turned by its bent portion 90 by means of the carriage rack 6, which is secured on a rocking lever 65.

On the left and right side of a machine base part 66, of which only one half is shown in Fig. 3, there is secured a bearing plate 68 behind the axle 67 of the key levers 44. Figs. 2 and 3. At the free end of the bearing plates 68 extending to the rear, there is rotatably mounted a tube 70 by means of pointed screws 69. On the tube 70 there is secured at the right end a lever 71 and at the left end a lever 72. In the levers 71 and 72 there is supported, by means of pointed screws 73, a tube 74 at the ends of which there is secured plates 75 and 76. The plates 75 and 76 slide with their front ends on a set screw 77, against which they are each pressed by a spring 78.

Between the plates 75 and 76 there are pivotally mounted on pointed screws 80, four tubes according to the embodiment of the invention. Each tube 79 carries a transmitting member 45, Figs. 2 and 3, each of which cooperates with a stop face of a switch lever 41. On each of the tubes 79 there is secured a control bar 81, preferably made of wire, which extends over the lateral range of all key levers 44. On each control bar 81 a vertical tension spring 82 reacts which extends downward until it strikes against a setscrew 83.

The right lever 71. Figs. 2 and 3, extends upward and is connected by a bar 84 with the shift key (not shown). A spring (not shown) urges the levers 71 and 72, the

plates 75 and 76, and the tubes 79 arranged between them in the direction of the arrow 85, Fig. 2. Thus the control bars 81 are displaced slightly to the front when the shift key is pressed down.

The frame consisting of the plates 75 and 76, the tubes 79 and the control bars 81 is adjustable by means of the setscrews 77. The control bars 81 are additionally adjustable by the setscrews 83.

The control bars are arranged above stop faces 86' of control extensions 86 which are provided on the key levers 44, and which extend beyond their axles 67 to the rear. In the key levers whose associated types have different widths in the. shifting position, one or two stop faces 86' of the associated control extension 86 are so arranged that they act on another control bar when the control bars 81 are displaced to the front.

When actuating a key, a control bar 81 is lifted, the associated tube 79 is turned counterclockwise, Fig. 2, and the transmitting member 45 secured thereon is lifted so that it presses on the stop 43 of the associated switch lever 41, lifting its stop face 42 into the path of the pawl tooth 27, Fig. 1.

In the embodiment shown in the drawing there are provided five different type widths. Naturally it is possible to provide, in a corresponding manner, more or less different type widths.

The method of operation of the device is as follows:

When a key is pressed down, the associated key lever 44 and with it the control extension 86 is turned clockwise, Fig. 2. The stop face 86' thus presses the control bar 81 upward. The tube 79 connected with the control bar 81 is turned in the opposite direction, Fig. 2. The transmitting member 45 secured on the tube 79 presses on the stop face 43 of the switch lever 41 and turns it against the action of the spring 46 with its stop face 42 into the path of motion of the bent-off portion 96 of the pawl 26. Due to the motion of the type bar (not shown) the switching element 11 is turned in known manner counterclockwise, and the fixed ratchet tooth 10 engages the escapement wheel 3. During this motion of the first switching element 11, the setscrew 16 acts on the bent-off portion 15 of the second switching element 12 and turns it clockwise against the action of the spring 14. In this motion the rocking lever 18 is actuated and also the pawl 26 and the pawl tooth 27. Thus the pawl tooth 27 is disengaged from the escapement wheel 3. The pawl 26 is now turned clockwise about the pivot 28 by the springs 31 and 32 until its bent-off portion 96 strikes against the stop face 42 of the switch lever 41, which has been brought into its path of motion.

When the type bar returns, the second switching element 12 and the first switching element 11 are turned back under the action of the spring 14 so that the fixed ratchet tooth 10 is disengaged from the escapement wheel 3 and the pawl tooth 27 engages the escapement wheel 3. The carriage is now displaced in known manner by the carriage tension spring (not shown) and the carriage driving wheel 4, which engages the carriage rack 6, drives the escapement wheel which carries along the pawl tooth 27. This step motion of the carriage is limited in this way that the pawl tooth 27 strikes with the stop face 100, Fig. 4, against the fixed stop 37.

When the space key (not shown) is pressed down, the push rod 57, Fig. 2, connected with it, is moved in the direction of the arrow 89 and its lower lug 56 presses on the flange 55 of the stirrup 49 which is thus turned clockwise about the axle or pin 50 against the force of the spring 52. The leg 53 of the stirrup 49 acts in this case from the bottom on an associated switch lever 41, which is turned counterclockwise about the shaft 40 against the force of the spring 46, while its stop face 42 moves into the path of motion of the pawl tooth 27. At the same time, the lug 59 of the push rod 57 presses on the first switching element 11, so that the switch step of the carriage is released in the above described man- I161. Due to the connection with one of the switch levers 41, a carriage step of predetermined length is thus achieved by the space key. The device makes it possible to arrange additional space keys in a simple manner, which cooperate with other switch levers 41 and which therefore release several switch step lengths of the carriage.

If the rocking lever 65 actuated by the carriage release, Fig. 5, is turned counterclockwise, the carriage rack 6 secured thereon moves into the position indicated by the broken lines in Fig. 5. It strikes against the bent portion 90 of the lever 64, which is rotated in the direction of the arrow 91. Due to the forked recess 61 and the bent portion 60 of the rocking lever 18, the latter is turned clockwise, Fig. 1, about the journal 19, until the pin 22 strikes against the lower edge of the recess 24 of the second switching element 12. In this motion of the rocking lever 18, the pawl 26 secured thereon moves downward in the direction of the arrow 92 so that the pawl tooth 27 is disengaged from the escapement wheel 3. The pawl tooth 27 moves therefore forward under the action of the springs 31 and 32 until it strikes against the stop 97. The carriage is now free and can be manually shifted at will. If the carriage release is operated after the shifting of the carriage, the latter is moved by the carriage tension spring in the step direction to the next step position. The slide spring 21 lifts the rocking lever 18 through the bolt 20, Fig. 1, so that the pawl tooth 27 engages again the escapement wheel 3 and stops the carriage after the pawl tooth 27 strikes against the stop 37.

When the carriage is returned manually or by the return key, the pawl tooth 27 is also disengaged from the escapement wheel 3 in the above described manner by the slide spring 21 and, after the motion is completed, it engages the escapement wheel 3 again. Due to the arrangement of the stop 97, Fig. 1, for the pawl tooth 27, the latter is only turned by a short distance after disengagement from the escapement wheel, so that, after it returns to the escapement wheel 3, only a short idle step has to be performed by the pawl tooth 27 and thus also by the carriage until the rest position is attained.

I claim as my invention:

1. A device for recording business machines for variable letter spacing, comprising an escapement wheel, a switching element rockably mounted about an axis crossing the axis of the escapement wheel, a fixed ratchet tooth on the switching element, means for rocking the switching element for engaging the fixed ratchet tooth with and disengaging it from the teeth of the escapement wheel, a second switching element rockably mounted about an axis crossing the axis of the escapement wheel, a pawl mounted upon a pivot connected with the secondmentioned switching element, and means for rocking the second-mentioned switching element for engaging the pawl with and disengaging it from the teeth of the escapement wheel, said pivot being arranged laterally of the escapement wheel for guiding the engaging part of the pawl in a concave curvature relative to the axis of the escapement wheel.

2. A device according to claim I, in which the pawl pivot lies within a cylindrical plane surrounding the teeth of the escapement wheel and is substantially parallel to the axis of the escapement wheel and said pawl being arranged at a slight distance from the escapement wheel.

3. A device according to claim 1, in which the escapement wheel is provided with a plurality of teeth, and in which a stop for the pawl is provided for completing the switch step, said stop being arranged adjacent the teeth of the escapement wheel.

4. A device according to claim 1, in which the escapement wheel is provided with a plurality of teeth, and in which a stop for the pawl is provided for completing the switch step, said stop being arranged adjacent the teeth of the escapement wheel, the stop for completing the switch step surrounding the teeth of the escapement wheel on two sides.

S. A device according to claim 1, in which the pawl has a tooth consisting of a thin steel plate which is integral with the pawl and which is formed by a bent-off portion thereof.

6. A device according to claim 1, in which the pawl has a tooth consisting of a thin steel plate which is integral with the pawl and which is formed by a bentofi' portion thereof, and in which the bent-01f portion has a stop face for completing the switch step.

7. A device according to claim 1, in which the escapement wheel is provided with a plurality of teeth, and in which a stop is provided for completing the switch step arranged adjacent the teeth of the escapement wheel, the stop lying substantially in the plane of the stop face of said fixed ratchet tooth.

8. A device according to claim 1, in which a carriage driving wheel and a carriage rack are provided with the escapement wheel being provided with more teeth than thafc of the carriage driving wheel engaging the carriage rac 9. A device according to claim 1, in which a switch gear frame and a plurality of switch levers are provided arranged side by side on the switchgear frame and arranged perpendicularly to the axis of the escapement wheel, said switch levers being provided each with a stop face for the pawl.

10. A device according to claim 1, in which a rocking lever is provided so that the pivot of the pawl is supported thereby.

11. A device according to claim 1, in which key levers are provided and at least one control bar is provided actuated by the key levers to adjust the step lengths of the pawl.

12. A device according to claim 1, in which two tension springs of different initial stress are provided, said springs being connected to the pawl so as to act thereon at different points and in different directions, to force the pawl to jump forward.

13. A device according to claim 1, in which said pivot lies within a cylindrical plane surrounding the teeth of the escapement wheel and substantially parallel to the axis of the escapement wheel, said pawl being arranged at a slight distance from the escapement wheel, and in which a rocking lever and a special stop are provided with said pivot being supported by the rocking lever and the jump of the pawl after the shifting of the rocking lev being limited by the special stop.

Nvice according to claim 1, in which control bars are provided to adjust the step length of the pawl and in which key levers mounted on axles are provided with control extensions extending beyond their axles for cooperation with the control bars.

15. A device according to claim 1, in which control bars are provided to adjust the step length of the pawl and in which key levers mounted on axles are provided with control extensions extending beyond their axles for cooperation with the control bars, and in which interme diate members and a shift key are provided with the control bars being capable of being shifted forward and backward by the intermediate members actuated by the shift key.

16. A device for recording business machines for variable letter spacing, comprising an escapement wheel, a switching element rockably mounted about an axis crossing the axis of the escapement wheel, a fixed ratchet tooth on the switching element, means for rocking the switching element for engaging the fixed ratchet tooth with and disengaging it from the teeth of the escapemerit wheel, a second switching element rockably mounted about an axis crossing the axis of the escapement wheel, a pawl mounted upon a pivot connected with the secondmentioned switching element, means for rocking the second-mentioned switching element for engaging the pawl with and disengaging it from the teeth of the escapement wheel, said pivot being arranged laterally of the escapement wheel for guiding the engaging part References Cited in the file of this patent of the pawl in a concave curvature relative to the axis UNITED STATES PATENTS of the escapement wheel, a switch lever, control bars to 342 H adjust the step length of the pawl by means of the switch 23: a 1 May 1886 lever, key levers mounted on axles provided with control 5 2 1 Deweu 1907 extensions extending beyond their axles for cooperation i5 suiikney 1938 with the control bars, intermediate members, a shift key 2 :33::

with the control bars being capable of being shifted forward and backward by the intermediate members actuated by the shift key, and a space key provided to operate 10 the switch lever independently of the control bars. 

